The ring-form trophozoites have one (and rarely two) chromatin dots and a cytoplasm ring that tends to be thicker than P. falciparum. ‘Bird’s-eye’ forms may appear. There is no enlargement of infected RBCs.
In the developing trophozoites of P. malariae, the chromatin is rounded or streaky and the cytoplasm is usually compact and does not contain a vacuole. The pigment may be coarse and peripheral. A 'band" forms as the trophozoites mature and the cytoplasm elongates across the host RBC.
Images courtesy of the CDC.
